Invalid username

I couldn't logged in using KL Kam starting from yesterday but I don't know why. I have been trying to log in to PF for about 20 times but it didn't allow me to do so. I just signed up using PFF as my new username and wanted to send PM to Greg to tell him about this, but the system automatically used KL_Kam instead of PFF to be my new username. I'm really confused. [?]

Edit: I thought is it because I was banned but I don't think so because I haven't received any warning private message from Greg before and I don't think I've broken PF regulations.

Edit 2:
I just checked the member list and my old account KL Kam still exists.

I can log in as KL_Kam (new account) by just typing KL Kam (old account) as log in name.